Drapeable and launderable light weight flame retardant barrier fabrics

ABSTRACT

Flame retardant (FR) nonwoven fabrics and methods of producing same are provided. An FR nonwoven fabric includes FR rayon and either FR polyester or FR polypropylene or any blend thereof. The FR nonwoven fabric has a basis weight less than 3 ounces per square yard, and is devoid of non-FR binder material. The FR nonwoven fabric displays substantial flame retardant properties after five home launderings in accordance with protocols set forth in AATCC Test Method 135-1995. The FR nonwoven fabric is configured to maintain flame and heat resistant integrity when impinged with a gas flame in accordance with testing protocols set forth in Technical Bulletin 604 of the State of California Department of Consumer Affairs (TB-604), and to maintain flame and heat resistant integrity when impinged with a gas flame in accordance with testing protocols set forth in National Fire Protection Agency 701-1989 test method.

RELATED APPLICATION

This application claims the benefit of and priority to U.S. ProvisionalPatent Application No. 60/652,582 filed Feb. 14, 2005, the disclosure ofwhich is incorporated herein by reference as if set forth in itsentirety.

FIELD OF THE INVENTION

The present invention relates generally to fabrics and, moreparticularly, to flame retardant fabrics.

BACKGROUND OF THE INVENTION

There is heightened awareness of fire prevention in homes and businessesin the United States. This awareness has led to the development ofstandards and legislation directed to reducing the risk of fires,particularly with respect to bedding and upholstered furniture.Conventional fire prevention techniques for bedding and upholsteredfurniture involve the topical application of flame retardant (FR)chemicals directly to an outer decorative layer of upholstery material.

California Technical Bulletin 603 of the State of California Departmentof Consumer Affairs (hereinafter “TB-603”), which is incorporated hereinby reference in its entirety, exposes the top and side panels of amattress to an open gas flame to simulate the effects of burningbedclothes. TB-603 is extremely aggressive relative to conventionalcigarette burn tests and many industry analysts are skeptical thatconventional fabrics used to upholster furniture and bedding products(e.g., mattresses, etc.) will be able to pass TB-603.

Because of TB-603, the furniture and bedding industries have been forcedto utilize FR barrier fabrics capable of passing TB-603, e.g., treatedor coated fabrics, and fabrics comprised of inherently FR fibers.Barrier fabrics capable of satisfying TB-603 can be lofty, can requirethe use of binder fibers, and/or can have a high basis weight.

California Technical Bulletin 604 of the State of California Departmentof Consumer Affairs (hereinafter “TB-604”), which is incorporated hereinby reference in its entirety, uses a small flame, such as thatrepresentative of a pillow case burning, to challenge a barrier fabricpositioned between the flame and a fiber/foam filling. The advent ofTB-604 has generated a need for a new type of barrier fabric—one that islaunderable and more drapeable than current FR barrier fabrics. Thisneed arises because pillows and comforters generally experience betweenfive and ten home launderings (which can wash off the FR chemicals) intheir life time and because consumers prefer soft pillows andcomforters. Furthermore, a fabric which can act as a TB-604 FR barrierfabric in a pillow or comforter need not be thick and insulative becausethese materials will not experience the tremendous heat flux of a TB-603flame.

FR rayon, when incorporated into a fabric, contributes to the formationof a barrier-forming char when the fabric is exposed to flame. However,binder fibers (e.g., latex binder fibers) are conventionally required tohold FR rayon into a nonwoven structure. See, for example, U.S. PatentApplication Publication No. 2004/0102112, which describes a fabric heldtogether by between 6% and 25% of non-FR low melt binder fiber or latexresin. Unfortunately, because they are combustible, binder fibers aredeleterious to the flame retardant performance of the fabric.

Therefore, rayon is conventionally treated by topically applying (e.g.,spraying or padding) chemicals thereon that react with the rayon.Unfortunately, topical FR treatment of rayon/polyester blended nonwovenfabrics or rayon/polypropylene blended fabrics have been hamperedbecause FR treatments that work on rayon may not work on polypropyleneor on polyester. Similarly, FR treatments that work on polypropylene oron polyester may not work on rayon. Thus, in order to effectively treata rayon/polyester or a rayon/polypropylene blended fabric with FRchemicals, it is necessary to finish the fabric twice or to treat boththe rayon and the polyester or polypropylene in a single bath. However,this process results in the chemicals intended to treat the rayonwashing off of the polyester and polypropylene during laundering and thechemicals intended for the polypropylene and polyester washing off ofthe rayon during laundering. Thus there is a tremendous inherent wasteof chemicals and resultant pollution when nonwoven rayon/polyesterfabrics or nonwoven rayon/polypropylene fabrics are topically treatedwith FR chemicals.

In addition, it is hard to crosslink FR chemicals to cellulose fiberswithin a fabric containing rayon. In order to form a covalent bond withcellulose, formaldehyde releasing agents (or other crosslinking agentssuch as aziridine, epoxy or urethane containing products) are oftenemployed. Alternatively, an acid or base catalyst can be utilized toforce etherification or esterification of cellulose; however, thesecatalysts must be subsequently rinsed out so as not to cause yellowingor tenderizing of a fabric, and to prevent the fabric from causingallergic reactions in users of the fabric.

U.S. Patent Application Publication No. 2004/0097156 describes a fabricof at least 5 ounces per square yard which is composed of a blend of FRrayon, FR acrylic and FR melamine fibers. U.S. Patent ApplicationPublication No. 2004/0097156 describes a structure similar to U.S.Patent Application Publication No. 2004/0102112 but with the addedrequirement that the basis weight be over 5 ounces per square yard.

SUMMARY OF THE INVENTION

In view of the above discussion, flame retardant (FR) nonwoven fabricsand methods of producing same are provided. According to someembodiments of the present invention, an FR nonwoven fabric includes FRrayon and either FR polyester or FR polypropylene or any blend thereof.The FR nonwoven fabric has a basis weight of less than 3 ounces persquare yard, and is completely devoid of non-FR binder material. The FRnonwoven fabric displays substantial flame retardant properties afterfive home launderings in accordance with protocols set forth in AATCCTest Method 135-1995. In addition, the FR nonwoven fabric is configuredto maintain flame and heat resistant integrity when impinged with a gasflame in accordance with testing protocols set forth in TechnicalBulletin 604 of the State of California Department of Consumer Affairs(TB-604), and to maintain flame and heat resistant integrity whenimpinged with a gas flame in accordance with testing protocols set forthin National Fire Protection Agency 701-1989 test method.

According to some embodiments of the present invention, an FR nonwovenfabric includes between about 10% and 90% FR rayon and between about 10%and 90% FR polyester. According to some embodiments of the presentinvention, an FR nonwoven fabric includes between about 10% and 90% FRrayon and between about 10% and 90% FR polypropylene.

According to some embodiments of the present invention, a method ofproducing FR nonwoven fabric includes blending FR polypropylene fibersand FR rayon fibers, forming a web of the blended polypropylene andrayon fibers, heating the web to a temperature sufficient to causeadjacent polypropylene fibers to bond together, and calendaring theheated web. The FR polypropylene fibers are 2 denier, 2 inch fibers andthe FR rayon fibers are 1.5 denier, 2 inch fibers. The rayon fiberscomprise between about 10% and 90% of the blend and the polypropylenefibers comprise the remaining percentage (i.e., between about 10% and90% of the blend).

According to some embodiments of the present invention, a method ofproducing FR nonwoven fabric includes blending FR polyester fibers andFR rayon fibers, forming a web of the blended polyester and rayonfibers, heating the web to a temperature sufficient to cause adjacentpolyester fibers to bond together, and calendaring the heated web. TheFR polyester fibers are 2 denier, 2 inch fibers and the FR rayon fibersare 1.5 denier, 2 inch fibers. The rayon fibers comprise between about10% and 90% of the blend and the polyester fibers comprise the remainingpercentage (i.e., between about 10% and 90% of the blend).

According to some embodiments of the present invention, a method ofproducing FR nonwoven fabric includes blending FR polypropylene fibersand FR rayon fibers, forming a first web of the blended polypropyleneand rayon fibers, wherein the fibers are oriented in a machinedirection, forming a second web of the blended polypropylene and rayonfibers, wherein the fibers are oriented in a cross direction, andbonding the first and second webs together. The FR polypropylene fibersare 2 denier, 2 inch fibers and the FR rayon fibers are 1.5 denier, 2inch fibers. The rayon fibers comprise between about 10% and 90% of theblend and the polypropylene fibers comprise the remaining percentage(i.e., between about 10% and 90% of the blend). The first and secondwebs are bonded together in any of various ways including, but notlimited to, thermal bonding, stitch bonding, hydroentangling orspunlacing, and needlepunching.

According to some embodiments of the present invention, a method ofproducing FR nonwoven fabric includes blending FR polyester fibers andFR rayon fibers, forming a first web of the blended polyester and rayonfibers, wherein the fibers are oriented in a machine direction, forminga second web of the blended polyester and rayon fibers, wherein thefibers are oriented in a cross direction, and bonding the first andsecond webs together. The FR polyester fibers are 2 denier, 2 inchfibers and the FR rayon fibers are 1.5 denier, 2 inch fibers. The rayonfibers comprise between about 10% and 90% of the blend and, thepolyester fibers comprise the remaining percentage (i.e., between about10% and 90% of the blend). The first and second webs are bonded togetherin any of various ways including, but not limited to, thermal bonding,stitch bonding, hydroentangling or spunlacing, and needlepunching.

FR nonwoven fabric, according to embodiments of the present invention,has a low basis weight, is drapeable, is environmentally friendly and islaunderable. Moreover, FR nonwoven fabric, according to embodiments ofthe present invention, does not include any combustible components suchas binder fibers and latex binders. FR nonwoven fabric, according toembodiments of the present invention, requires no further need fortreatment in order to comply with TB-603 and TB-604.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-4 are flow charts of methods of producing FR nonwoven fabric,according to some embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention now is described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. The terminology used in thedescription of the invention herein is for the purpose of describingparticular embodiments only and is not intended to be limiting of theinvention. As used in the description of the invention and the appendedclaims, the singular forms “a”, “an” and “the” are intended to includethe plural forms as well, unless the context clearly indicatesotherwise. As used herein, the term “and/or” includes any and allcombinations of one or more of the associated listed items.

As used herein, phrases such as “between X and Y” and “between about Xand Y” should be interpreted to include X and Y. As used herein, phrasessuch as “between about X and Y” mean “between about X and about Y.” Asused herein, phrases such as “from about X to Y” mean “from about X toabout Y.”

As used herein, the term “flame resistant material” means a materialthat passes the requirements of National Fire Protection Association(NFPA) 701-1989.

As used herein, the term “drapeable” means non-self supporting ornon-stiff. That is, a drapeable fabric when placed on top of an objectwill drape down upon the object.

According to embodiments of the present invention, a drapeable FRnonwoven fabric includes a blend of FR rayon fibers and FR polyesterfibers, or a blend of FR rayon fibers and FR polypropylene fibers andhas a basis weight less than 3 ounces per square yard. For example, theFR nonwoven fabric may include between about 10% and 90% FR rayon fibersand between about 10% and 90% FR polyester fibers. Alternatively, the FRnonwoven fabric may include between about 10% and 90% FR rayon fibersand between about 10% and 90% FR polypropylene fibers. Moreover, FRnonwoven fabric, according to embodiments of the present invention, isdevoid of combustible material such as, for example, latex bindermaterial, non-FR binder fibers, etc. Exemplary FR rayon fibers areavailable from Lenzing AG, Austria; exemplary FR polyester fibers areavailable from Far Eastern Textile, Ltd., Taipei, Taiwan; and exemplaryFR polypropylene fibers are available from FiberVisions, Covington, Ga.

FR nonwoven fabric, according to embodiments of the present invention,is configured to display substantial flame retardant properties afterfive home launderings in accordance with protocols set forth in AATCC(American Association of Textile Chemists and Colorists) Test Method135-1995 (e.g., machine cycle=delicate, wash temperature=27±3° C., linedry). In addition, FR nonwoven fabric, according to embodiments of thepresent invention, is configured to maintain flame and heat resistantintegrity when impinged with a gas flame in accordance with testingprotocols set forth in Technical Bulletin 604 of the State of CaliforniaDepartment of Consumer Affairs (TB-604), and when impinged with a gasflame in accordance with testing protocols set forth in National FireProtection Agency 701-1989 test method.

According to embodiments of the present invention, nonwoven fabric, suchas thermal bond nonwoven fabric, spunlaced nonwoven fabric, stitchbonded nonwoven fabric, or needlepunched nonwoven fabric, is providedthat is comprised entirely of either a blend of FR rayon and FRpolyester or of a blend or FR rayon and FR polypropylene. Applicantshave discovered how to select and control the following parameters suchthat rayon/polyester and rayon/polypropylene blended FR fabrics canachieve desired end use properties such as wash durability, flameretardancy, char formation and soft drapeable hand and without theinherent problems of conventional FR fabrics: fiber denier, fiberlength, opening process, blending process, carding process andconsolidation (spunlace, stitch bond and needlepunch), bonding (thermalbond) parameters. In addition, rayon/polyester and rayon/polypropyleneblended FR fabrics, according to embodiments of the present invention,may utilize prodegradants, crimped fibers, fibers with amorphous andcrystalline zones, bicomponent fibers, sheath core fibers, fibers withhigh or low modulus, short or long fibers, low or high denier fibers,mixtures of different types of fibers, fiber treatments, fibers withdifferential melting rates and differential melting points, etc.

Referring to FIG. 1, a method of producing FR nonwoven fabric, accordingto some embodiments of the present invention, includes blending FRpolypropylene fibers and FR rayon fibers (Block 100), forming a web ofthe blended polypropylene and rayon fibers (Block 110), heating the webto a temperature sufficient to cause adjacent polypropylene fibers tobond together (Block 120), and calendaring the heated web (Block 130).According to some embodiments of the present invention, the FRpolypropylene fibers are 2 denier, 2 inch fibers and the FR rayon fibersare 1.5 denier, 2 inch fibers. According to some embodiments of thepresent invention, the rayon fibers comprise between about 10% and 90%of the blend and the polypropylene fibers comprise the remainingpercentage (i.e., between about 10% and 90% of the blend). According tosome embodiments of the present invention, calendaring the heated web(Block 130) may be performed via various types of calendar rolls suchas, for example, patterned calendar rolls.

Referring to FIG. 2, a method of producing FR nonwoven fabric, accordingto some embodiments of the present invention, includes blending FRpolyester fibers and FR rayon fibers (Block 200), forming a web of theblended polyester and rayon fibers (Block 210), heating the web to atemperature sufficient to cause adjacent polyester fibers to bondtogether (Block 220), and calendaring the heated web (Block 230).According to some embodiments of the present invention, the FR polyesterfibers are 2 denier, 2 inch fibers and the FR rayon fibers are 1.5denier, 2 inch fibers.

According to some embodiments of the present invention, the rayon fiberscomprise between about 10% and 90% of the blend and the polyester fiberscomprise the remaining percentage (i.e., between about 10% and 90% ofthe blend). According to some embodiments of the present invention,calendaring the heated web (Block 230) may be performed via varioustypes of calendar rolls such as, for example, patterned calendar rolls.

Referring to FIG. 3, a method of producing FR nonwoven fabric, accordingto some embodiments of the present invention, includes blending FRpolypropylene fibers and FR rayon fibers (Block 300), forming a firstweb of the blended polypropylene and rayon fibers, wherein the fibersare oriented in a machine direction (Block 310), forming a second web ofthe blended polypropylene and rayon fibers, wherein the fibers areoriented in a cross direction (Block 320), and bonding the first andsecond webs together (Block 330).

According to some embodiments of the present invention, the FRpolypropylene fibers are 2 denier, 2 inch fibers and the FR rayon fibersare 1.5 denier, 2 inch fibers. According to some embodiments of thepresent invention, the rayon fibers comprise between about 10% and 90%of the blend and the polypropylene fibers comprise the remainingpercentage (i.e., between about 10% and 90% of the blend).

The fibers in the first web are oriented along the machine direction ofthe first web, i.e., along the lengthwise direction of the first web.The fibers in the second web are oriented along the cross direction ofthe second web, i.e., along the widthwise direction of the second web.The first and second webs are bonded together (Block 330) in any ofvarious ways including, but not limited to, thermal bonding, stitchbonding, hydroentangling or spunlacing, and needlepunching. Spunlacing,stitch bonding, needle punching, and thermal bonding are well understoodby those skilled in the art and need not be described herein.

Referring to FIG. 4, a method of producing FR nonwoven fabric, accordingto some embodiments of the present invention, includes blending FRpolyester fibers and FR rayon fibers (Block 400), forming a first web ofthe blended polyester and rayon fibers, wherein the fibers are orientedin a machine direction (Block 410), forming a second web of the blendedpolyester and rayon fibers, wherein the fibers are oriented in a crossdirection (Block 420), and bonding the first and second webs together(Block 430).

According to some embodiments of the present invention, the FR polyesterfibers are 2 denier, 2 inch fibers and the FR rayon fibers are 1.5denier, 2 inch fibers. According to some embodiments of the presentinvention, the rayon fibers comprise between about 10% and 90% of theblend and the polyester fibers comprise the remaining percentage (i.e.,between about 10% and 90% of the blend).

The fibers in the first web are oriented along the machine direction ofthe first web, i.e., along the lengthwise direction of the first web.The fibers in the second web are oriented along the cross direction ofthe second web, i.e., along the widthwise direction of the second web.The first and second webs are bonded together (Block 430) in any ofvarious ways including, but not limited to, thermal bonding, stitchbonding, hydroentangling or spunlacing, and needlepunching.

The following examples are not intended to limit the scope of thepresent invention, but are set forth as examples of embodiments of thepresent invention.

EXAMPLES Example 1

Thermal Bond Nonwoven Fabric Production

2 denier, 2 inch FR polypropylene fibers are weighed into fiber blendingequipment and mixed with a desired amount of 1.5 denier, 2 inch FR rayonfibers to accomplish thorough mixing of the fiber blend. The resultingblend is conveyed using an air conveyer system to opening equipmentwhich further separates the fibers and lays them down in thick batt orweb. Then the web is conveyed on a belt to a carding machine that usescounter rotating teeth or wires to further refine and compress the web.The web is then conveyed on a belt to a forced air or infrared oven orto a through air heating dryer. The supported web is rapidly raised to ahigh enough temperature to melt the outer sheath of the polypropylenefiber in order to cause it to bond with adjacent polypropylene fibersand to some extent with the FR rayon fibers. The web is then conveyedout of the oven or heating chamber and may either be calendared using apatterned calendar roll or cooled and rolled up. Between 10% and 90% ofFR polypropylene is recommended for use in the thermal bonding processdescribed above with the remainder of the fiber being FR rayon in orderto produce a strong enough flame resistant barrier to meet the end userequirements of TB-604 barrier products. The above experiment may alsobe performed by substituting FR polyester for the FR polypropylene.

Example 2

Stitch Bond Nonwoven Fabric Production

2 denier, 2 inch FR polypropylene fibers are weighed into fiber blendingequipment and mixed with a desired amount of 1.5 denier, 2 inch FR rayonfibers to accomplish thorough mixing of the fiber blend. The resultingblend is conveyed using an air conveyer system to opening equipmentwhich further separates the fibers and lays them down in thick batt orweb. Then the web is conveyed on a belt to a carding machine that usescounter rotating teeth or wires to further refine and compress the web.In order to achieve a more uniform ratio of machine direction (MD) tocross direction (XD) oriented fibers in the nonwoven fabric, it may bedesirable to produce two carded fiber batts one of which is oriented inthe machine direction relative to the spunlacing equipment with theother being cross lapped over the first web. Other processes may also beused to form the unconsolidated web including drafting, consolidating orstretching the fiber batt. Next the fiber batt is passed through aprocess in which filament yarn on a warp beam is threaded throughneedles that stitch or knit through the fiber batt. The stitching orknitting process consolidates the fibers in the fiber batt and binds thefibers together to form a strong composite fabric. This process is knownas stitch bonding, as would be understood by those skilled in the art.

Example 3

Spunlaced Nonwoven Fabric Production

2 denier, 2 inch FR polypropylene fibers are weighed into fiber blendingequipment and mixed with a desired amount of 1.5 denier, 2 inch FR rayonfibers to accomplish thorough mixing of the fiber blend. The resultingblend is conveyed using an air conveyer system to opening equipmentwhich further separates the fibers and lays them down in thick batt orweb. Then the web is conveyed on a belt to a carding machine that usescounter rotating teeth or wires to further refine and compress the web.In order to achieve a more uniform ratio of MD to XD oriented fibers inthe nonwoven fabric, it may be desirable to produce two carded fiberbatts one of which is oriented in the machine direction relative to thespunlacing equipment with the other being cross lapped over the firstweb. Other processes may also be used to form the unconsolidated webincluding drafting, consolidating or stretching the fiber batt. Next thefiber batt is passed under high pressure water jets which are used toconsolidate and hydroentangle the fibers in the web in a process whichis well known to those familiar with the art of spunlacing.

Example 4

Needlepunched Nonwoven Fabric Production

2 denier, 2 inch FR polypropylene fibers are weighed into fiber blendingequipment and mixed with a desired amount of 1.5 denier, 2 inch FR rayonfibers to accomplish thorough mixing of the fiber blend. The resultingblend is conveyed using an air conveyer system to opening equipmentwhich further separates the fibers and lays them down in thick batt orweb. Then the web is conveyed on a belt to a carding machine that usescounter rotating teeth or wires to further refine and compress the web.In order to achieve a more uniform ratio of MD to XD oriented fibers inthe nonwoven fabric, it may be desirable to produce two carded fiberbatts one of which is oriented in the machine direction relative to thespunlacing equipment with the other being cross lapped over the firstweb. Other processes may also be used to form the unconsolidated webincluding drafting, consolidating or stretching the fiber batt. Next thefiber batt is passed under bank of reciprocating needles that aredesigned to consolidate and entangle the fibers in the web in a processwhich is well known to those familiar with the art of needlepunching.

1. A flame retardant (FR) nonwoven fabric, comprising between about 10%and 90% FR rayon and between about 10% and 90% FR polyester, wherein theFR nonwoven fabric has a basis weight less than 3 ounces per squareyard, and wherein the FR nonwoven fabric is devoid of non-FR bindermaterial.
 2. The FR nonwoven fabric of claim 1, wherein the FR nonwovenfabric is manufactured using a process selected from the groupconsisting of hydroentangling, stitch bonding, needle punching, andthermal bonding.
 3. The FR nonwoven fabric of claim 1, wherein the FRnonwoven fabric displays substantial flame retardant properties afterfive home launderings in accordance with protocols set forth in AATCCTest Method 135-1995.
 4. The FR nonwoven fabric of claim 1, wherein theFR nonwoven fabric maintains flame and heat resistant integrity whenimpinged with a gas flame in accordance with testing protocols set forthin Technical Bulletin 604 of the State of California Department ofConsumer Affairs (TB-604).
 5. The FR nonwoven fabric of claim 1, whereinthe FR nonwoven fabric maintains flame and heat resistant integrity whenimpinged with a gas flame in accordance with testing protocols set forthin National Fire Protection Agency 701-1989 test method.
 6. A flameretardant (FR) nonwoven fabric, comprising between about 10% and 90% FRrayon and between about 10% and 90% FR polypropylene, wherein the FRnonwoven fabric has a basis weight less than 3 ounces per square yard,and wherein the FR nonwoven fabric is devoid of non-FR binder material.7. The FR nonwoven fabric of claim 6, wherein the FR nonwoven fabric ismanufactured using a process selected from the group consisting ofhydroentangling, stitch bonding, needle punching, and thermal bonding.8. The FR nonwoven fabric of claim 6, wherein the FR nonwoven fabricdisplays substantial flame retardant properties after five homelaunderings in accordance with protocols set forth in AATCC Test Method135-1995.
 9. The FR nonwoven fabric of claim 6, wherein the FR nonwovenfabric maintains flame and heat resistant integrity when impinged with agas flame in accordance with testing protocols set forth in TechnicalBulletin 604 of the State of California Department of Consumer Affairs(TB-604).
 10. The FR nonwoven fabric of claim 6, wherein the FR nonwovenfabric maintains flame and heat resistant integrity when impinged with agas flame in accordance with testing protocols set forth in NationalFire Protection Agency 701-1989 test method.
 11. A method of producingflame retardant (FR) nonwoven fabric, comprising: blending FRpolypropylene fibers and FR rayon fibers; forming a web of the blendedpolypropylene and rayon fibers, wherein the web has a basis weight lessthan 3 ounces per square yard; and heating the web to a temperaturesufficient to cause adjacent polypropylene fibers to bond together. 12.The method of claim 11, further comprising calendaring the heated webvia a patterned calendar roll.
 13. The method of claim 11, wherein theFR polypropylene fibers are 2 denier, 2 inch fibers and wherein the FRrayon fibers are 1.5 denier, 2 inch fibers.
 14. The method of claim 11,wherein blending FR polypropylene fibers and FR rayon fibers comprisesblending between about 10% and 90% FR rayon fibers and between about 10%and 90% FR polypropylene fibers.
 15. A method of producing flameretardant (FR) nonwoven fabric, comprising: blending FR polyester fibersand FR rayon fibers; forming a web of the blended polyester and rayonfibers, wherein the web has a basis weight less than 3 ounces per squareyard; and heating the web to a temperature sufficient to cause adjacentpolyester fibers to bond together.
 16. The method of claim 15, furthercomprising calendaring the heated web via a patterned calendar roll. 17.The method of claim 15, wherein the FR polyester fibers are 2 denier, 2inch fibers and wherein the FR rayon fibers are 1.5 denier, 2 inchfibers.
 18. The method of claim 15, wherein blending FR polyester fibersand FR rayon fibers comprises blending between about 10% and 90% FRrayon fibers and between about 10% and 90% FR polyester fibers.
 19. Amethod of producing flame retardant (FR) nonwoven fabric, comprising:blending FR polypropylene fibers and FR rayon fibers; forming a firstweb of the blended polypropylene and rayon fibers, wherein the fibersare oriented in a machine direction; forming a second web of the blendedpolypropylene and rayon fibers, wherein the fibers are oriented in across direction; and bonding the first and second webs together to forma composite web having a basis weight less than 3 ounces per squareyard.
 20. The method of claim 19, wherein the FR polypropylene fibersare 2 denier, 2 inch fibers and wherein the FR rayon fibers are 1.5denier, 2 inch fibers.
 21. The method of claim 19, wherein bonding thefirst and second webs together comprises stitch bonding the first andsecond webs.
 22. The method of claim 19, wherein bonding the first andsecond webs together comprises spunlacing the first and second webs. 23.The method of claim 19, wherein bonding the first and second webstogether comprises needlepunching the first and second webs.
 24. Amethod of producing flame retardant (FR) nonwoven fabric, comprising:blending FR polyester fibers and FR rayon fibers; forming a first web ofthe blended polyester and rayon fibers, wherein the fibers are orientedin a machine direction; forming a second web of the blended polyesterand rayon fibers, wherein the fibers are oriented in a cross direction;and bonding the first and second webs together to form a composite webhaving a basis weight less than 3 ounces per square yard.
 25. The methodof claim 24, wherein the FR polyester fibers are 2 denier, 2 inch fibersand wherein the FR rayon fibers are 1.5 denier, 2 inch fibers.
 26. Themethod of claim 24, wherein bonding the first and second webs togethercomprises stitch bonding the first and second webs.
 27. The method ofclaim 24, wherein bonding the first and second webs together comprisesspunlacing the first and second webs.
 28. The method of claim 24,wherein bonding the first and second webs together comprisesneedlepunching the first and second webs.